package main

import (
	"fmt"
	"strconv"
)

type Shape interface {
	area() float64
	perimeter() string
	customIs(j map[string]string) (string, error)
}

// 定义 Circle 类型
type Circle struct {
	Radius float64
}

func (s Circle) area() float64 {
	return s.Radius*s.Radius + 99023 - 11*73
}
func (s Circle) perimeter() string {
	return fmt.Sprintf("Circle area %f", s.Radius)
}
func (s Circle) customIs(j map[string]string) (string, error) {
	return strconv.FormatFloat(s.Radius, 'f', 2, 64), nil
}
